Rontgen apparatus



July 12, 1938. c. Nil-:MANN ET Al.

RNTGEN APPARATUS FiledV Feb. 4, 19:57

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Patented July 12, 1938 UNITED STATES PATENT OFFIQE RNTGEN APPARATUSApplication February 4, 1937, Serial No. 124,081 In Germany February 1S,1936 5 Claims.

This invention relates to Rntgen apparatus, and is particularlyconcerned with novel and improved means for operating Rntgen tubes withhigh tension, such as applied, for example, in 5 deep therapy. Theinvention is especially directed to the provision of apparatusfurnishing complete high tension and irradiation protection andcharacterized by relatively small weight and greatly reduced dimensions.In order to attain these objects, the Rntgen tube is connected directlyto the alternating current furnished by a high tension transformer,thereby dispensing with the usual valve tubes and disposing the Rntgentube and the high tension transformer in a single protective housing orin two separate housings which are, however, closely connected to form aunitary structure. The high tension protective housing (or housings) isfilled with a suitable insulating medium, such as 20 oil, in order toreduce the dimensions further. One pole of the Rntgen tube and of thehigh tension transformer is conductively connected with the groundedexterior wall of the protective housing` This provision is particularlyadvantageous in case of grounding of the anode of the Rntgen tube,because the cooling of the anode can be accomplished in a simple mannerdirectly from the grounded water supply.

The state of the art is briefly noted below and 70 compared with the newstructure, so that the invention may be fully understood andappreciated.

Devices are known wherein the Rntgen tube and the high tensiontransformer are provided in 5 a common grounded and oil-filled containerand equipped with a grounded water-cooled anode. It should be observed,however, that these known structures are not suitable for high tensionoperation as required in deep therapy because, while 40 the anode of theRntgen tube is dielectrically relieved at the grounded anode end, thetube is subjected to the full operating tension at the cathode end. Inorder to prevent dielectric breaks and gas eruptions, it would benecessary to di- 45 mension the housing at the cathode end of the tubeso large that the apparatus would be unsuitable for practical operation.

It is possible, however, in accordance with the present invention, evenin case of such a struc- 50 ture as intimated above, to keep thedistance between the tube and the grounded housing very small bysurrounding the tube with annular or tubular metallic members. Thelatter are arranged so that the distribution of the tension 55 withinthe protective housing is substantially ap- (Cl. Z50- 34) proximated tothe normal distribution of tension along the tube due to the capacityeiect of the ring-shaped members. By normal distribution of tensionalong the tube is meant that tension distribution which occurs upon freeoperation ofthe tube, and not upon operation within a grounded housing.This tension distribution is determined by the structure of the tube,and is particularly affected by conditions permitting electrons emittedfrom the electrodes to strike l0 and charge the glass wall of the tube.

The provision of capacitatively coupled internal and external shieldsbroadly in conjunction with gas-filled discharge tubes is likewiseknown, for the purpose of avoiding undesired gas discharges. However,such provisions are applied only with freely operated tubes and not withtubes disposed within a high tension protective housing wherein thedetrimental influence of the grounded housing wall upon the normaltension distribution along the tube is to be compensated for orequalized.

Another known structure may be noted wherein the middle or centralportion of a Rntgen tube disposed within a grounded oil-filledcontainer, is surrounded by a ring-shaped control electrode for thepurpose of preventing the formation of charges upon the outer surface ofthe tube. However, the Rntgen tube is connected in this arrangement todirect current with both 50' poles on high tension. The centralelectrode does not serve the purpose of reducing the load or stress uponthe tube wall by an electric alternating current eld.

The new arrangement of annular or tubular metallic bodies surroundingthe Rntgen tube, as disclosed herein, renders the advantage of keepingthe distance between the tube and the housing wall very small. Thelongitudinal extent of the housing may be reduced in accordance withanother feature of the present invention by using a Rntgen tube having apractically linear normal tension distribution, i. e., a tube whereinthe longitudinal tension load (kV per cm of tube length) is smallest.Linear tension distribution along the tube may be attained by providingfor a structure wherein the electrons emanating from electrodes cannotdisturb the linear tension distribution formed normally under theinnuence of the operating current. Rntgen tubes provided with electrodehoods, double-walled tubes, and tubes with especially thick walls may bementioned as examples of such structures. Tubes wherein the glass wallis subdivided by metallic members or intermediate electrodes, such asthe so-called cascade tubes, should not be used because their dimensionsare too large for the instant purposes.

The invention may also be of advantage in devices wherein both poles ofthe Rntgen tube are connected to high tension. If desired or required,the potentials of the ring-shaped or tubular metallic members may becontrolled separately from the outside by connecting thereto suitablecurrent. Capacitative control of the potentials will, however, sufficein most general cases of use. Exterior control may necessitateundesirable increase of the size of the tube due to the space requiredfor the highly insulated current conductors for the corresponding metalmembers.

The following detailed explanations are rendered with reference to theaccompanying drawing illustrating an embodiment of the invention for thepurpose of guiding others in its practical use. The drawing shows asomewhat schematic representation, partly in section, of a Rntgen tubeand associated equipment, including the high tension transformer and theprotective housing.

Referring now to the drawing, numeral l designates a metal container inwhich is disposed the high tension transformer with its primary winding3, secondary winding 4, and iron core 5. The terminals of the primarywinding are indicated at 3a. One pole of the secondary winding,indicated at 6, is grounded. The high tension current is conducted tothe cathode l@ of the Rntgen tube Il from the other pole of thesecondary winding by means of the metal conduit l, which may be highlyinsulated, for example, by means of paper bandages 8, and which isjoined to the metallic member i8b. The latter is connected to thecathode I0 by a conductor 9a. Conductor 9b is a low voltage tap of thesecondary winding and supplies heating current for the cathode. TheRntgen tube IlV is disposed in a grounded container l2, which is joinedwith the container l at I3, for example, by a soldered joint. The anodeI4 of the Rntgen tube Il is grounded and can therefore be cooled ina'simplegmanner by circulating waterfrom a grounded water supply throughthe cooling pipe I5. Y Y

The focal point of the Rntgen tube Il is surrounded by an electronprotective hood i6 having an aperture l'l provided with a berylliumdisk. 'Ihe Rntgen rays can therefore emanate substantially without losswhile the electrons are retained. In case of irradiation of bodycavities, the anode will take a tubular form, projecting in generallyknown manner from the container substantially centrally of the tube withthe focal point provided at the end thereof.

The Rntgen tube Il is surrounded by ringshaped, annular or tubularmetallic members i8 embedded within paper bandages I9 and therebyinsulated from each other. Other suitable insulating means may be used,if desired. The ends or rims 20 of these metallic members it areenlarged in order to prevent a spraying effect, and overlap each otherso that they assume charges by the influence of their potentials whichcorrespond substantially to the normal tension distribution along thetube. The metallic members lila and |8bare conductively connected withthe anode and with the cathode, respectively, of the Rntgen tube.

The container portions or receptacles l and l2 are filled with oil orwith another suitable high grade insulating medium in order to providefor the smallest possible dimensions of the structure. It is advisablefor this purpose to dispose the Rntgen tube Il within a casing or pot 2lwhich may be made of a suitable insulating material, such as porcelain,pressed material or plexigum, and the like. The Rntgen tube is thusseparated from the tubular or annular bodies I8, whereby its removal orreplacement is considerably facilitated, with the further advantage ofpreventingmixture of the oil surrounding the Rntgen tube Il with the oilcontained in the receptacle or housing l2, and thus substantiallyreducing the danger of detrimental discharges of the tube afterreplacement thereof.

It may be desirable to ground the cathode instead of the anode andthereby simplify the arrangement for heating the cathode. In such a casethe anode would be connected with the high tension pole of the hightension transformer and would dissipate the heat by radiation.

The structure described in the foregoing is par ticularly adapted fordeep therapy, but can also be applied for technical examination ofmaterials with hard Rntgen rays.

Changes may be made, deviating from the precise showing of the structureillustrated in the drawing and described in the foregoing, and thereforeit is understood that all embodiments are considered our invention,provided they fall within the spirit and scope of any or all of theappended claims, subject only to the showing of the prior art.

We claim as our invention:

1. Rntgen apparatus comprising an evacuated tube containing cathode andanode electrode elements, said elements being supported from oppositeends of said tube, respectively, a source of high tension currentconnected between said elements, a metallic protective housingsurrounding said tube, said housing being connected to the anode andbeing of such small dimensions that at the cathode end where the fullanode potential appears between the housing and cathode the spacing isinsuicient to prevent disruptive discharges, means for preventing suchdischarges comprising a series of annular metallic rings insulated fromeach other and surrounding said tube from end to end inside the housing,and means connecting the two opposite end members of the series to thecathode and anode, respectively, whereby said rings constitute acapacitative shunt of the discharge path between said elements.

2. Rntgen apparatus comprising an evacuated tube containing electrodeelements, a source of high tension current having its two polesconnected to said elements, respectively, to produce discharge currents,a metallic protective housing conductively connected to one pole of saidsource and surrounding said tube at such a close distance therefrom asto tend to affect the discharge path between said elements, and meansfor preventing said housing from thus affecting the operation of thetube, said means comprising a series of annular metallic members insidesaid housing and surrounding said tube from end to end, said membersbeing insulated from each other and the opposite end members beingconnected to said elements, respectively, whereby the said members forma capacitative shunt of the discharge path between said elements.

3. Rntgen apparatus comprising an evacuated tube containing electrodeelements, a housing for said tube comprising an inner shell ofinsulating material and an outer shell of conducting material, said tubebeing positioned within said inner shell, a series of overlappingannular metallic members positioned in the annular space between saidshells, said members being insulated from each other, and connectionsfrom the opposite end members of said series to said electrode elements,respectively, whereby the said elements constitute a capacitative shuntof the discharge path between said electrodes.

4. Rntgen apparatus comprising a metallic housing, an inner shell ofinsulating material located in said housing, said shell being smallerthan the housing so that an annular space is provided between the shelland the inner wall of the housing, a Rntgen tube removably positionedwholly inside said shell, a series of annular overlapping metallicmembers packed in the said annular space, and insulating wrappings forsaid members to prevent conductive contact between them.

5. Rntgen apparatus comprising a Rntgen tube provided with cathode andanode, a protective metallic housing surrounding said tube and havingits wall relatively close to the wall of the tube, a source of hightension current having one pole connected to said housing and to theanode of said tube and having the other pole connected to the cathode ofsaid tube, an annular metallic member surrounding said tube at one end,a second metallic member surrounding said tube at the other end, aplurality of intermediate annular metallic members surrounding said tubebetween said first and second members, all said members being insidesaid housing and being insulated from each other, a conductiveconnection from said rst member to said housing and anode, and aconductive connection from the second member to said cathode.

CARL NIEMANN. KURT BISCHOFF.

